Roles of osmolytes in plant adaptation to drought and salinity

Abstract

Drought and salinity are an immense threat to crop production worldwide, and crop growth models predict that due to global climate change the frequency and severity of drought and salinity stresses will be more severe in the future to cause substantial damages. Drought, salinity and other abiotic stresses are the reasons for crop losses worldwide as much as 50 %. So, it is a burning concern to protest and prevent the destructive global effects of drought and salinity. To cope with the stresses, plants, however, adopt a variety of physiological and biochemical mechanisms at the cellular and whole organism levels. Under these stress conditions, many plants and organisms synthesize and accumulate compatible solute compounds termed as osmolytes or osmoprotectants. Osmoprotectants are small, electrically neutral non-toxic molecules at molar concentrations and highly soluble organic compounds that efficiently maintain osmotic balance and stabilize proteins and membranes under salt, drought or other stress conditions. Researches in metabolomic, polyomic, transcriptomic and transgenic levels explored that plants overexpressing osmolyte biosynthesis or metabolic genes showed enhanced stress tolerance. This chapter presents information highlighting the vital roles of osmoprotectants against the devastating effects of drought and salt stresses.